Most diseases of the eye are treated with topical ophthalmic solutions containing pharmaceutical agents. It has been postulated that delivery and efficacy of these agents would be greatly increased if the agents were incorporated in ophthalmic lenses and those lenses were used as drug delivery devices. These agents may be added to the ophthalmic lenses by a variety of methods including soaking the agent into a formed lens, adding the agent to the formulation of the lens prior to its formation and the like. Others have postulated methods of testing the uptake and discharge rates of such pharmaceutical agents to and from the ophthalmic lenses. These methods include placing ophthalmic lenses in solutions and monitoring the concentration of the pharmaceutical agent over time. Even though these methods work, due to the volume of solution used in the test, the conditions do not mimic the conditions that an ophthalmic lens is exposed to when inserted into an ocular environment.
In an ocular environment, very small volumes of tear fluid pass over the lens during its use. Therefore it would be beneficial if one could mimic those conditions to test the performance of ophthalmic lenses. This need is met by the following invention